As I understand it, it does not matter if your vessel is wood, aluminum, fiberglass, steel, or plastic.... The danger of lightning on the water is meaningful. Lightning does not discriminate when it comes to boat makes and types. The only fool proof way to mitigate the risk of a strike is by getting to port and off your boat as soon as possible. Here is some info I found on google.
http://boatsafe.com/nauticalknowhow/lightning.htm